As is well-known, systems, such as mechanical, hydraulic, or electrical systems, are utilized to perform a variety of functions. Each system typically includes an assemblage of objects or devices united by some form of regular interaction or interdependence to provide a specified function. For example, this assemblage may constitute a plurality of mechanisms, each of which may have to be controlled in an orderly manner for the system to operate as desired.
Controls, either manual or automatic, are normally employed to actuate the mechanisms. While a system may include a single control for actuating a plurality of mechanisms, it is not unusual that one motion of the control, such as a rotary motion, is used to actuate these mechanisms. This may not be entirely satisfactory to ensure independent actuation of each mechanism should that be needed for the system. Moreover, if the control is manually operable, and is required to be operated often over a period of time, then it also may be important that the control be able to be manipulated relatively easily, smoothly and comfortably to reduce the likelihood of operator fatigue.
As one example of a system, consideration may be given to vehicles such as fork lift trucks which are in wide use for handling and moving articles between various locations. In the operation of these vehicles, it is often required that the vehicle be simultaneously steered and driven, and that the fork lift be simultaneously actuated to pick up and deliver articles from one station to another. Consequently, during the course of the operation of a fork lift truck, the operator will be busy manipulating various controls to perform these functions.
Generally, it has been found useful to enable the operator to accomplish such functions by making use of the operator's feet and hands. For example, mechanisms governing the direction of the truck via the transmission, and engine speed, can be regulated with a pedal control which can be rotated or pivoted by the operator's feet, thereby freeing the operator's hands for manipulating other controls for the steering of the vehicle and the activation of a fork lift mechanism. This single rotary motion of the pedal control however, may not adequately enable the vehicle operator to independently regulate the direction and speed. Also, since the operator can be stationed on the truck for an extended period of time and may have to constantly actuate the controls for performing such functions, it is not unlikely that the operator may become fatigued. However, the prior controls such as the pedal control have not been designed necessarily to make their manipulation relatively easy, smooth and comfortable so as to reduce the likelihood of fatigue.